Design, synthesis, and assembly of composite liquid crystal elastomer fibers

非技术总结：可以响应于外部刺激而显著改变尺寸、从二维（2D）到三维（3D）的形状、体积和物理性质的软材料对于广泛的潜在应用具有极大的兴趣。植物可以通过细胞壁的预编程各向异性变形来实现复杂的响应变形，细胞壁由不同刚度的分层排列的纤维聚合物制成。该项目旨在通过编程纤维聚合物的各向异性来模拟细胞壁的结构和功能，同时探索生物学中普遍存在的分子异质性和相分离。该研究将促进聚合物科学与工程，软物质物理和机械工程学科之间的协同作用，以开发复杂，多组分，多相网络。研究成果将在下一代智能传感器、执行器、软机器人、智能可穿戴设备和3D显示器中产生潜在的应用。它还将成为招聘和培训各级学生的有效工具。将特别强调代表性不足的群体在校园开展研究。最新的研究成果将在费城材料日和宾夕法尼亚科学咖啡馆项目上展示。聚合物网络的形状变形和重塑将创造一个重要的推广机会，激发公众的兴趣，从而激发和吸引人们对科学、技术、工程和数学（STEM）的兴趣。将组织一次专题讨论会，介绍研究成果，并促进来自学术、工业和国家实验室的研究人员的互动。技术概要：计划中的研究是基于多管齐下的活动，包括设计、合成、组装、制造、表征和一套独特的环境响应聚合物的性能优化。 这些是液晶弹性体及其纤维形式的复合材料，具有精确控制的成分，分子取向，结构和从纳米到宏观尺度的机械响应。重要的是，这项研究将提供一个关于如何在分子水平上动态配置材料固有特性的整体视图，即化学组成，相分离和交联梯度，同时保持微观到宏观尺度的几何控制的视野。多组分、多相网络将拓宽材料调色板，以创建具有精确控制的材料弹性各向异性的更复杂结构。响应外部刺激的复杂形状将被创建以模仿植物细胞壁结构和功能，并具有可调光子颜色和机械适应性等奖金。研究成果将丰富将局部可控自由度与全局几何、形状和变形路径联系起来的基础知识。这些见解可能有助于开发下一代复合纤维，用于智能传感器，执行器，3D显示器，软机器人和智能纺织品等潜在应用。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

NON-TECHNICAL SUMMARY:Soft materials that can dramatically change size, shape from two-dimensional (2D) to three-dimensional (3D), volume, and physical properties in response to external stimuli are of great interest for a wide range of potential applications. Plants can achieve complex responsive morphing via a pre-programmed anisotropic deformation of cell walls, which are made of hierarchically arranged fibrous polymers of different stiffness. This project aims to mimic the cell wall structures and functions by programming the anisotropy in fibrous polymers, while exploring molecular heterogeneity and phase separation that are ubiquitous in biology. The research will foster synergistic interactions across disciplines of polymer science and engineering, soft matter physics, and mechanical engineering to develop complex, multi-component, multi-phased networks. The research outcome will lead to potential applications in next generation smart sensors, actuators, soft robots, smart wearables, and 3D displays. It will also act as an effective tool to recruit and train students at all levels. Special emphasis will be given to underrepresented groups to carry out research on campus. The latest research results will be showcased at the Philadelphia Materials Day and Penn Science Café Program. Shape morphing and reshaping of the polymer networks will create a significant outreach opportunity to excite the general public, thereby provoking and engaging interest in Science, Technology, Engineering, and Mathematics (STEM). A symposium will be organized to feature research outcome and facilitate interactions with researchers from academic, industrial and national labs.TECHNICAL SUMMARY:The planned research is based on multi-pronged activities, including design, synthesis, assembly, fabrication, characterization, and property optimization of a unique set of environmentally responsive polymers. These are liquid crystal elastomers and their composites in the form of fibers with precisely controlled compositions, molecular orientations, architectures and mechanical responses from nano- to macroscales. Importantly, the research will offer a holistic view on how to dynamically configure the material’s intrinsic properties at the molecular level, that is chemical composition, phase separation, and crosslinking gradient, while keeping sights of geometric controls at the micro- to macroscale in the form of cylindrical confinement. The multi-component, multi-phased networks will broaden the materials palette to create more complex structures with precisely controlled anisotropy in material elasticity. Complex shapes in response to an external stimulus will be created to mimic plant cell wall structures and functions, with bonuses such as tunable photonic colors and mechanical adaptivity. The research outcome will enrich fundamental knowledge that relates the locally controllable degrees of freedom to the global geometries, shapes and shapeshifting paths. The insights could contribute to the development of the next generation composite fibers for potential applications such as smart sensors, actuators, 3D displays, soft robots, and smart textiles. .This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.